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Laser-controlled modifications of the structure and topology of the surface layers of a solid that are used to obtain specific characteristics in objects for various purposes are considered. Structural phase transitions induced in a solid by laser radiation are analyzed, depending on the size of nanoparticles (nanoclusters). The propagation of surface states is modeled in the context of the diffusion model and cellular automata.

The functional physical characteristics (electrophysical and optical properties) of a thin-film nanocluster system upon a change in the topology/morphology of surface solid structures are considered. Features of the fundamental physical effects in such systems allow us to talk about a new area of research: topological photonics, which has undoubted practical promise, particularly in the field of femtosecond nanoelectronics.

We report on the fabrication of fractal dendrites using laser-induced melting of aluminum alloys. We target boron carbide (B4C), which is one of the most effective radiation-absorbing materials characterized by a low coefficient of thermal expansion. Due to the high fragility of B4C crystals, we were able to introduce its nanoparticles into a stabilization aluminum matrix of AA385.0. The high-intensity laser field action led to the formation of composite dendrite structures under the effect of local surface melting. Modelling the dendrite cluster growth confirms its fractal nature and sheds light on the pattern behavior of the resulting quasicrystal structure.

The formation of macroscale carbon structures characterised by an sp-sp2-hybridization is realised by self-assembly in colloidal solutions under an effect of laser irradiation and electromagnetic fields. The sponge-like morphology, sculptured with gold nanoparticles (NPs) was revealed by Scanning Electron Microscopy (SEM) imaging. Full structural and defect characterization of the self-assembled sponges was provided using the micro-Raman spectroscopic technique. The synthesized clusters manifest themselves in the presence of a strong spectral band in the visible range of the photoluminescence spectra that is quite unusual for ordered sp2-carbon systems.

We predict an optical effect associated with systems which exhibit topologically protected states separated by a finite distance. We develop a tight-binding model to calculate the optical selection rules in linear chains of atoms of different lengths, and show the crucial importance of edge states. For long enough molecules the interband transitions involving these edge states are in the highly sought-after THz frequency range. Although we have specifically considered finite carbon chains terminated by gold nanoparticles, the main results of our work can be generalized to various systems which exhibit topologically protected states separated by a finite distance., 9 Pages, 4 Figures

Functional physical properties of laser-induced nanocluster structures of different topology in the thin films deposited on solid surface and 3D-crystallic structures by femto-nanoexperiments are studied. Physical basis and specific topology nanocluster view are under our consideration with regard to the functional properties variation (electrophysics + optics) in granular structures. Modeling of electronic energy levels modification due to the topology factors and nonlinear dynamic model for coupled electronic states in the cluster system are carried out. New physical principles for possible application of such structures of topological photonics with different element compositions are discussed.

We stabilize monoatomic carbon chains in water by attaching them to gold nanoparticles (NPs) by means of the laser ablation process. Resulting nanoobjects represent pairs of NPs connected by multiple straight carbon chains of several nanometer lengths. If NPs at the opposite ends of a chain differ in size, the structure acquires a dipole moment due to the difference in work functions of the two NPs. We take advantage of the dipole polarisation of carbon chains for ordering them by the external electric field. We deposit them on a glass substrate by the sputtering method in the presence of static electric fields of magnitudes up to 10^5 V/m. The formation of one-dimensional carbyne quasi-crystals deposited on a substrate is evidenced by high-resolution TEM and X-ray diffraction measurements. The original kinetic model describing the dynamics of ballistically flowing nano-dipoles reproduces the experimental diagram of orientation of the deposited chains., 15 pages, 7 figures

Shungite carbon (ShC) nanoparticles in the form of stable aqueous dispersions represent a promising solution for optical and biomedical applications. The dispersion is an interesting phenomenon from the point of view of stabilization of ShC nanoparticles and their structural constituents up to the basic structural unit, namely a graphene fragment. Herein, we used these aqueous dispersions with easily released structural components to study laser irradiation with various durations and obtain hybrids of ShC with Ag and Au nanoparticles. The main role in the stabilization of ShC nanoparticles belongs to the graphene fragments and their stacks, which display a considerable dipole moment. Newly prepared aqueous dispersions of ShC–metal hybrid nanoparticles retained the stability inherent in the original nanoparticles both of ShC and metals. Changes in the size distribution pattern of nanoparticles in dispersions upon ablation were studied by dynamic light scattering (DLS). Raman with UV-Vis spectroscopy methods were applied to trace structural changes in ShC upon the formation of hybrid nanoparticles. Films obtained by condensation of the dispersions on glass substrates display periodic structures, as was revealed by SEM microscopy. There, the conditions under which nanoparticles lose their ability to disperse in water and retain a graphene-like structure in a film were revealed.

The physical properties of solid structures depending on the boundary conditions in topologically ordered nanocluster systems are discussed. These systems are synthesized using various laser methods in the form of metal/semiconductor nanostructures/nanoclusters and thin films on solid substrates. A particular attention is paid to the possible mechanisms and tendency to high-temperature superconductivity in these thin-film nanocluster structures.

The conductivity of thin films composed by clusters of gold and silver nanoparticles has been studies in a wide range of temperatures. The switch from a temperature independence to an exponential thermal dependence of the conductivity manifests the crossover between the tunnel and thermally activated hopping regimes of the electronic transport at the temperature of 60 °C. The characteristic thermal activation energy that governs hopping of electrons between nanoparticles is estimated as 1.3 eV. We have achieved a good control of the composition and thicknesses of nano-cluster films by use of the laser ablation method in colloidal solutions.

In the article we introduce the experiment of the photostimulation effect in the tunneling conductivity of free-standing thin carbyne-gold films. We observe a sharp increase of the conductivity of hybrid film due to the electromagnetic exciting at the frequencies which are close to the plasmon resonance of gold nanoparticles. The use of carbyne threads as a stabilizing matrix makes it possible to obtain free-standing thin films that demonstrate a good structural stability. The tunnel current–voltage measurements demonstrate a strong dependence of the current value on the intensity of green laser radiation used to photostimulate thin C–Au in area of the measuring experiment.

An experimental method for fabrication of a nanocomposite metamaterial based on a self-assembly of titanium dioxide microtubes with encapsulated gold nanoparticles (NPs) is proposed. The formation of microtubes is induced by laser irradiation in the presence of an external magnetic field. It is shown that the variation of the metal NP concentration leads to the increase of the optical absorption of the metamaterial. The possibility of using arrays of oriented microtubes as absorbing n-doped layers for solar cells is demonstrated.

We consider experimentally and theoretically the detection of quantum states in nanocluster semiconductor/metal structures upon the registration of hopping/tunneling electrical conductivity and possible mechanisms of realization of such states. We obtain nanostructured thin films on the substrates using different technologies, including laser ablation of solid surfaces. We show that it is possible to control the properties of the films by varying the topology of such synthesized systems. We analyze the features arising due to the specific conductivity of granular media revealed by the measured current–voltage characteristics and electrical resistance dependences for nanocluster bimetallic films of different compositions.

Methods of laser modification allow us to observe macroscopic quantum phenomena in nanostructured (cluster) materials. The laser synthesis of nanoparticles/nanoclusters with different topologies in semiconductor PbTe samples is performed via direct laser modification of thin films under the action of continuous laser radiation with a wavelength of 1.06 μm and a power density of ~105 W/cm2. Nanoparticles with bimodal distribution in lateral dimensions are obtained on the surfaces of the samples. The electrophysical properties of such structures can be controlled as desired by modifying their topology. Variations in electric properties depending on the particle location density are demonstrated. The results are interpreted based on the existence of quantum coherent processes with tunneling transitions and hopping conductivity. This approach is promising for the fabrication of elements and devices in optoelectronics and photonics based on new physical principles, and of different hybrid optoelectrical schemes.

We used the nonlinear hydrodynamic model of the motion of molten flows to determine the basic geometric characteristics of the resulting coatings in a laser experiment. To test the capabilities of the developed algorithm, a series of calculations was performed for various values of Reynolds numbers (Re) and certain sizes of the computational domains with several cavities with different configurations. The influence of the channel geometry is clearly noticeable in the case of a deep depression. The direction of motion of different structures (e.g. the vortex) was predicted. Using the convection model, we estimate the temperature field and velocity distribution in the system under consideration for various initial conditions and experimental regimes selected. The profile of the arising island on the surface was modeled by a scaling computational domain with the number of particles N = pS, where the parameter p – determined the viscosity of melted material, and S - the area of the computational domain. The influences of the two key parameters, i.e. probability of adhesion (sc) and viscosity (p), on the obtained surface profile of materials can be estimated by our approach, and result in different deposition images, being finally principal for functional characteristics of the samples under the specific regimes of laser treatment.

We applied a controlled method for producing nanostructures on glass substrates. We made detailed measurements to control the resulting micro-and nanostructures using as the principal example of surface modification of glassy carbon compositions under laser irradiation. The properties of the samples after laser irradiation were studied using atomic force microscopy (AFM) with an accuracy of about 10 nm in the scanning plane. The results of probing the material modification by the AFM images of its surface have been considered in frame of the nonlinear hydrodynamic mathematical approach and computer simulation.

Models of the formation of roughnesses on the surface of materials and the movement of distributed flows in their presence are considered, which ultimately determines the functional properties of such topological materials of different compositions induced by laser radiation. The paper also presents simulation of crystallization of complex structures from a melt with an analysis of the morphology of the resulting crystalline structures, and shows examples of the occurrence of fractal dendritic formations. Different types of morphology are induced depending on the energy of the laser radiation and the duration of the heating; determining the final state of objects with the desired functional and structural characteristics. Using the methods of cellular automata, the models were obtained for both the distribution of crystallization centers and the growth of an individual cluster under the influence of diffusion mechanisms. The relationship between the resulting morphology and the modified parameters of the models used is analyzed.

We experimentally realize nano-antennas based on hybrid silicon-gold nanoparticles (NPs). The silicon particles covered by clusters of small metal NPs are fabricated from a liquid phase under the effect of the laser irradiation. The complex nanoclusters containing both Si and Au components provide the enhancement of the near-field intensity and the resonant light scattering associated with excitation of multipole resonances in NPs. A strong sensitivity of the resonant light absorption to the hybrid particle size and material parameters is experimentally documented and theoretically discussed. The results demonstrate a high potentiality of the hybrid NPs for the realization of functional optical devices and metasurfaces.

We studied monoatomic linear carbon chains stabilised by gold nanoparticles attached to their ends and deposited on a solid substrate. We observe spectral features of straight chains containing from 8 to 24 atoms. Low temperature PL spectra reveal characteristic triplet fine-structures that repeat themselves for carbon chains of different lengths. The triplet is invariably composed of a sharp intense peak accompanied by two broader satellites situated 15 and 40 meV below the main peak. We interpret these resonances as an edge-state neutral exciton, positively and negatively charged trions, respectively. The time-resolved PL shows that the radiative lifetime of the observed quasiparticles is about 1 ns, and it increases with the increase of the length of the chain. At high temperatures a non-radiative exciton decay channel appears due to the thermal hopping of carriers between parallel carbon chains. Excitons in carbon chains possess large oscillator strengths and extremely low inhomogeneous broadenings., Comment: 23 pages, 5 figures

The formation of hybrid silicon-gold NPs as a result of the laser action on a mixed colloidal solution is observed. These hybrid NPs are characterized by the amplification and broadening of the near-field photoluminescence spectra compared to pure silicon NPs. A strong sensitivity of the spectral shape of the emitted light to the intensity of the exciting white light is documented. These results may be used for the realization of functional metasurfaces consisting of randomly distributed resonant NPs. Moreover, as the synthesized NPs emit in red, green and yellow they can be used for fabrication of luminescent color screens.

In this paper, the results of laser formation of nanostructures of titanium dioxide are presented. The obtained structures were modified by a nanoparticle of gold and silver. The spectra of titanium dioxide with gold and silver nanoparticles are shown.

Metal-carbon materials realize surface-enhanced Raman scattering. Such structures were synthesized using the laser irradiation of colloidal systems consisting of carbon and noble metal nanoparticles.

We present the experimental and theoretical results of the study of laser modification of the solid phase of thin epitaxial films of lead telluride under continuous irradiation. An ensemble of nanoparticles with bimodal distribution depending on the laser power, beam diameter, and scanning rate of the surface is formed under laboratory conditions The process of the laser heating of a thin film is simulated, and the change in the temperature field, depending on the conditions of laser exposure, is described. The experimental results are interpreted based on the defect–deformation theory of the formation of a bimodal ensemble of nanoparticles under continuous laser irradiation. The diffusion model of cluster growth in the bulk and on the surface of a thin film demonstrates the possibility of forming a bimodal size distribution of clusters.

Tamm plasmons are confined optical states at the interface of a metal and a dielectric Bragg mirror. Unlike conventional surface plasmons, Tamm plasmons may be directly excited by an external light source in both TE and TM polarizations. Here we consider the one-dimensional propagation of Tamm plasmons under long and narrow metallic stripes deposited on top of a semiconductor Bragg mirror. The spatial confinement of the field imposed by the stripe and its impact on the structure and energy of Tamm modes are investigated. We show that the Tamm modes are coupled to surface plasmons arising at the stripe edges. These plasmons form an interference pattern close to the bottom surface of the stripe that involves modification of both the energy and loss rate for the Tamm mode. This phenomenon is pronounced only in the case of TE polarization of the Tamm mode. These findings pave the way to application of laterally confined Tamm plasmons in optical integrated circuits as well as to engineering potential traps for both Tamm modes and hybrid modes of Tamm plasmons and exciton polaritons with meV depth.

The drop deposition of colloidal nanoparticles was performed from water-based colloidal solutions. The proposed procedure is based on the agglomeration of colloidal particles in evaporation processes. The evaporation process was resulted in the formation of clustered thin films on a glass substrate. In the experiments with bimetallic Au:Ag solutions, the clustered films are grown, the formation of the clustered films with the average height of 100 nm was achieved. Optical properties of the deposited structures were investigated experimentally. It is shown that the obtained films may become transparent and their properties are defined by their morphology.

Metal-carbon materials realize surface-enhanced Raman scattering which has been synthesized by laser irradiation of colloidal systems consisting of carbon and noble metal nanoparticles. The dependence of the Raman scattering intensity of the material composition has been investigated. The possibility of detecting of the Raman spectrum of organic dye DCM and Rhodamine 6G was demonstrated.

By method of laser-induced thermal deposition of colloidal particles laser we have produced the metallic granular films for which the ability to control the change in its electrical properties does exist by variation of the topology for the system. The quantum states verification in cluster metallic structures by jump/tunneling electroconductivity and possible mechanisms for its implementation are considered in experiment and theory. The granular conductivity specificity has been under study. The current–voltage characteristics behavior has been measured for a gold (Au) and Au-carbyne clustered film. Two associated mechanisms for electroconductivity occur in the case, i.e. tunnel transition for electrons and electron activation in the frames of the shell model for a cluster system, in dependence on the nanostructure topology.

We present the results of experiments on the laser formation of metal microelectrodes of a fractal type on the surface of dielectrics. It is established that the electric resistance of microelectrodes significantly depends on their morphology and fractal dimension, which are determined by the parameters of laser processing. A new approach to analysis of the characteristics of conductivity in metal cluster structures of this type is proposed.

A long linear carbon chain (LLCC)/carbyne synthesis is principal in both theoretical and applied physics. In particular, in the controlling of electrophysical properties due to high polarizability. To synthesize an LLCC, one has to rely on the concept of the compensation process of instability for the linear chain (due to the form of globules and bundles) by some external interaction. In this paper we consider the features of laser experiments for solving the problem. Laser-induced LLCC in the colloidal system was obtained by irradiating a Shungite target in liquid and was stabilized by metal complexes. Some possible applications in nanophotonics are discussed in respect of high/hopping electroconductivity.

We have studied a solid-state laser modification of the surface of PbX semiconductor films under processes of self-organization for conditions when photon energies are above the band gap of the semiconductor. Experimental data were used to construct a model for defect deformation instability developing on the surface of epitaxial film through strain-induced drift of laser-induced point defects. The model is capable to describe qualitatively observed surface morphology and to predict the surface profile in laser modification experiments. It has been demonstrated that used approach is applied to analyze ant structure with various morphology which depends on parameters of laser action. By changing the electro-physical properties of the created structures in necessary direction we have a good opportunity to fabricate the new devices for optoelectronics and photonics of different kind.

This paper presents the results of experiments aimed at obtaining transparent carbon nanotube-nanofiber coatings by the laser irradiation of carbon targets in atmospheric air with a stream of ablated particles controlled by an external electric field and no metal catalyst.

We studied in both theory and experiment the nanocluster structures of different types (due to topology and composition) taking into account the correlations in nanoparticle-ensemble by quantum states. The problem of high temperature superconductivity due to topological surface structures with localized states has been under our consideration. Dramatic enhancement of electroconductivity (in six orders!), observed in our experiments, may be discussed as a real tendency to high temperature superconductivity due to topological peculiarities of nanocluster system. Near-field photoluminescence spectra/optical response in hybrid nanosystems measured by us demonstrated a big efficiency in the nanoantenna respect.

The synthesis of nanostructured metal–carbon materials by laser irradiation is an actual branch of laser physics and nanotechnology. Laser sources with different pulse duration allow to change the heating rate with realization of different transition scenarios and synthesis materials with various physical properties. We study the process of the formation of nanostructured metal–carbon clusters and complexes using laser irradiation of colloidal systems which have been consisted of carbon micro- nanoparticle and nanoparticle of noble metals. For carbon nanoparticle synthesis we use the method of laser ablation in liquid. For the realization of different regimes of laser surface modification of the target (glassycarbon and shungite) and the formation of micro- nanoparticle in a liquid the YAG:Nd laser with a pulse duration 0.5 ms up to 20 ms (pulse energy up to 50 J) was applied. We have used the CW-laser with moderate intensity in liquid (water or ethanol) for nanoparticle of noble metals synthesis. Thus, colloidal systems were obtained by using CW-laser with λ = 1.06 μm, I ~ 105–6 W/cm2, and t = 10 min. The average size of resulting particles was approximately about 10–100 nm. The nanoparticle obtaining was provided in the colloidal solution with different laser parameters. In this work we investigated the mechanism of the metal–carbon cluster formation during the process of colloidal system irradiation which has been consisted of separate carbon, silver and gold nanoparticles. This system was irradiated by nanosecond laser (100 ns) with average power up to 50 W.

The laser synthesis technique for producing nanoparticles/nanoclusters of different topology for semiconductor samples (PbTe) is presented by two laser ablation methods: direct laser modification of thin films and laser evaporation of substance from the target in liquid (ethanol) to produce a colloidal system, and the subsequent laser deposition of the particles from colloid on solid substrate [under continuous wave (cw)-laser, λ = 1.06 μm, laser intensity—up to 106 W/cm2]. Electro-physical properties of the induced structures have been controlled by various induced topology. It is obtained that electroresistance can dramatically decrease due to spontaneous selected multichannel/parallel electron transportation trajectories in the inhomogeneous cluster system. Two conditions are principal for that: the characteristic cluster size a

Results of the laser synthesis of carbon nanomaterials during the deposition of carbon vapors have been presented. One feature of this method is the action on the carbon samples in atmospheric air and external fields. Experiments on the laser action on the carbon targets in the presence of constant electric and inhomogeneous magnetic fields have been performed. The possibility of obtaining carbon micro- and nanofibers upon the deposition of particles in the electric field and carbon micro- and nanoclusters upon the deposition of particles in the magnetic field has been demonstrated. It has been shown that a change in the target material and action modes allows one to change the structure of the deposited layer.

Laser processing of epitaxial PbSe films has been found to produce periodic concentric surface ring structures that extend over several laser spot radii from the exposed zone. The proposed theoretical interpretation of this effect in terms of defect — deformation interactions adequately describes the observed morphology, periodicity and complex (multimode) shape of the ring structures.

Nanocluster structures can be easily modified in necessary direction and by controlled way in femtonanophotonics experiments. The variation of the key topology parameters can result in new type of the quantum correlation states/size effect for charged particles. In our earlier experiments we studied laser-induced topological nanoclusters structures of different types in thin films with unique phenomena in electrophysics and optics (see [1-3]). A simple 2-steps mechanism for enhancement of quantum behavior (e.g. in electroconductivity) exists for different conditions. First, when inelastic length linelastic > acluster we have no incoherent electron-phonon (e-ph) scattering, i.e. the coherent process takes place. Second, when de Broglie wave length λdB ≡ ℓcoh < Λ, (acluster – cluster size , Λ – spatial period of nanoparticle distribution) the coherent tunneling without loss occurs, and a long-range order with interference of the states takes place in the medium due to lattice structure.

An experimental method is developed for preparing nanostructures in the field of high-power laser radiation (~107 W cm-2) upon deposition of vapours of carbon-containing materials on a cold substrate surface. A specific feature of the method is irradiation of a sample in air at room temperature and pressure close to 1 atm. The dependences of the morphologic properties of nanostructures on the distance between a substrate and a sample are determined. Variations in the size of deposited nanostructures and their characteristic shape depending on the chosen material are found.

The video image of the graphite surface exposed to focused laser radiation is obtained with the help of a laser monitor. A bright ring moving over the heated surface was observed. A method for reconstructing the surface relief from the video image is proposed and realised. The method is based on the measurement of the angular distribution of the light intensity scattered by the graphite sample surface. The surface relief of the graphite sample changing in time is reconstructed. The relative change in the relief height during laser excitation is measured. The statistical characteristics of the reconstructed graphite surface shape and their variation during laser irradiation are studied. It is found that a circular convexity appears within the bright ring. The formation mechanism of this convexity requires further investigations.

Metal–carbyne materials, synthesized by laser irradiation of colloidal systems consisting of carbon and noble metal nanoparticles, are promising objects to realize surface-enhanced Raman scattering. The dependence of the Raman scattering intensity of the material composition has been investigated. The possibility of detecting of the organic dye Rhodamine 6G Raman spectrum was demonstrated.

We report for the first time the formation of a nanoparticle ensemble on a binary semiconductor (PbTe) film under cw laser irradiation. It is shown that defect — deformation theory of the formation of nanoparticle ensembles in the solid state under cw laser irradiation adequately describes experimental data. In particular, it predicts a bimodal nanoparticle size distribution function that agrees well with the experimental distribution function.

In this work the results of a bimetallic Au-Ag structure deposition from the colloidal system by nanosecond laser radiation are presented. The formation of the extended arrays of gold and silver nanoparticles with controlled morphology is examined. We report the results of formation bimetallic islands films with various electrical and optical properties. The changes in the optical properties of the obtained thin films are found to depend on their morphology.